10 F. R. Cowper Reed — Some Wenlock Species of Lichas. 



between second pair of pleurae and post-axial median piece ; each 

 third pleura ends in backwardly directed free point, and is crossed 

 by diagonal furrow making an angle of about 80°-90° with front 

 edge of pygidium. Free points of third pair of pleuree approximate 

 (not well preserved) ; margin of pygidium incurved, and shows on 

 under-surface concentric equidistant raised thread-like lines. 



Ornamentation consists of large round tubercles of two or three 

 graduated sizes, not very closely set. Owing to the breaking off 

 of the heads of the larger tubercles (which are hollow), circular 

 pits with a raised margin are left as cicatrices. 



Measurements. 



I 



(Fletcher's fis 

 Length of pygidium 

 Width of pygidium 

 Width of axis at front end 

 Length of axis ... 



Eemakks. — This species differs from L. Barrandii (Q. J.G.S., 1850, 

 vol. vi, pi. xxvii his, fig. 5) by the following features : (1) greater 

 relative length of pygidiuru, (2) narrower and shorter axis, 

 (3) only two axial rings, (4) no axial tubercle, (5) straight transverse 

 posterior furrow defining end of axis, (6) longer post-axial median 

 piece, (7) less backwardly curved pleurse, (8) course of furrows on 

 lateral lobes, (9) coarser tuberculation. 



The pygidium of L. scaber (Beyr.) bears a considerable resemblance 

 to that of L. Woodwardi. It may also be mentioned that the 

 ornamentation of L. Grayi, of which only the head-shield is known 

 from the Wenlock Limestone, is somewhat similar. 



Lichas (Dicranopeltis) Barrandei, Fletcher (emend.). 



lichas Barrandii, Fletcher {pars) : Q.J.G.S., 1850, vol. vi, p. 238, pi. xivii bis, 

 fig. 5 (non pi. xxvii, fig. 10). 



Fletcher's diagnosis of this species, with the exception of the 

 statement that "the incurved under-portion is concentrically striated," 

 which cannot be verified with our pi-esent material, applies to fig. 5, 

 pi. xxvii his, and does not need any amplification. It may, however, 

 be remarked that the figure is partly a restoration based on two 

 nearly complete specimens [b 28, h 29 in Salter's Catalogue), the 

 measurements of which are as follows : — 



1(5 29). 11(5 28). 



Length of pygidium ... ... ... 20 mm. ... 18 mm. 



Width (at front end) of pygidium ... ? ... 24 , , 



Width of axis (at front end) 13 ,, ... 11 ,, 



Leng-th of axis... ... ... ... 10 ,, ... ? 



It is unfortunate that of this species only the pj'gidium is known 

 at present. In one of the specimens (I) a faint transverse furrow, 

 incomplete in the middle, defines the posterior end of the axis, 

 recalling the much stronger furrow seen in L. Woodioardi. Fletcher 

 does not mention it, and it appears to be obsolete in the better 



